Half to



(ModeL) S. BERGMANN.

GONNEGTION FOR ELECTRIC LIGHT FIXTURES. No. 275,749.

Patented Apr. 10,1883.

INVENTOR WITNESSES 4& 5%

UNITED STATES PATENT OFFICE.

srennun B Re Auu, on NEW roux, n. Y., ASSIGNOB on ONE-HALF TO EDWARD n.JOHNSON, OF SAME PLACE.

CONNECTION FOR ELECTRIC-LIGHT FIXTURES.

SPEQIFICATIQH forming' part of Letters Patent No. 275,749, dated April10, 1883.

Application filed October 9, 1882. (Model) To all whom it may concern Beit known that I, SIGMUND BERGMANN, of the city, county, and State of NewYork, have invented a certain new and useful Improvement in Connectionsfor ElectricLight Fixtures, of which the following is a specification.

My invention relates to the connections of electrical drop-lights orstand-lamps which are connected by flexible wires with main or otherwires of a house. Such flexible wires are usually connected with theexterior terminals of a screw-plug which is adapted to enter a sockethaving corresponding interior terminals connected with the house-wires.Such socket may be the ordinary]amp-socket,attached to the arm of anelectrolier or wall-bracket; or it may be inserted in the wall, ceiling,or floor of the room. In the use of such plugs inconvenience isexperienced because in screwing them into the socket the flexible cordwhich contains the conducting-wires becomes twisted, which may cause itto break, or may bring the two conductors into contact and cause a shortcircuit.

The object of my invention is to obviate such inconvenience, which Iaccomplish by constructing a plug in which the part to which theconducting-wires are attached is station" ary, while the part whichcarries the termio nals corresponding with those of the socket isscrew-threaded and swiveled to the first part and provided with aprojecting key, by which it may be screwed in and out of the socketwithout afi'ecting the rest of the plu The stationary portion is a boxor casing of insulation having contact-plates within it and a suitableaperture or apertures, through which pass the flexible conductors whichare connected with said plates. The movable portion 0 consists of a plugof insulating material having a contact-plate at its end and ascrewthreaded contact-ring around it,'such plate and ring making contactwith corresponding terminals of a socket, as before mentioned,

4 5 and having sliding sprin g-connections with the contact-plates onthe stationary portion. One of such connections is a flat springattached to one of the plates within the outer casing and bearingagainst the inside of the band or ring terminal of the plug whichextends up beyond the insulating portion. From iheother or plateterminal of the plug a wire extends through said plug to a plate on itsupper surface, from which a metal rod extends up, making contact withthe second plate of the stationary casing and extending through anaperture in such casing. Preferably the outer end of the rod isscrew-threaded, and a thumb piece of insulating material is screwed ontosaid end, or otherwise secured thereto. A spiral spring is coiled aroundthe portion of the rod within the casing, and, being pressed against theupper plate of the plug and the plate on the inside of the casing, makesan additional contact between them. The plug maybe in- 6 serted in itssocket and screwed in or out by turning the thumb-piece without movingthe stationary casing and twisting the wires.

The above is illustrated in the annexed drawings, in which Figure 1 is aview in elevation of the plug inserted in its socket, the latter beingshown in section; Fig. 2, a section of the plug, and Fig. 3 a plan viewof the interior of the stationary box or casing.

A represents the stationary portion of the 7 plug, provided withinteriorcontact-plates, a b, to which are attached by means of bindingscrews thewires 0 (I, which are combined in the flexible cord B, running to a dropor stand lamp. From the plate I) a piece of lead wire, a, forming asafety-catch, runs to a plate, f, from which projects a fiat spring, g.The safetycatch may, however, be dispensed with, and the spring 5attached directly to plate Z).

O is the plug proper, carrying at its lower 8 end a contact-plate, la,and encircled by a screwthreaded band or ring, i. The spring y en tendsdownwardly such a distance that it will alwr ys he in contact with theband i. From contact-plate h a wire, j, passes through the plug 0 toplate 7., secured to the top of the pin A metal rod, 1, extends up fromplate It, passing through an aperture, m, in plate a, and extendingthrough box A. Its outer end is screw-threaded, and the thumb-piece D isscrewed tightly onto such end; or it may be attached in any othersuitable manner. A spiral spring, a, is coiled around rod 1, and ispressed against plates a and lit.

E is a socket for receiving the plug, having interior terminals, 0 p,corresponding with the terminals h i of the plug, and wires 1 2 run towarms the terminals 01). The plug is screwed into the socket by turningthe thumb-piece D and rod '5 while the part A is held stationary. Thecircuit is then by wire 1 contact-plates 0 7:, wire j, plate It, rod I,and springn to plate a, thence by Wire 0 to the lamp, returning by wiretl, plate I), safety-catch 6, plate f, spring g, screw-threaded band i,socket-terminal p, and wire 2.

What I claim is 1. In a connecting-plug for electric-light fixtures, thecombination of a stationary portion carrying terminals for makingconnection with an external circuit, a movable portion carrying exteriorterminals for making connection with corresponding terminals of asocket, and electrical connections between said stationary terminals andsaid movable terminals, substantially as set forth.

2. The combination with the outer stationary casing, of thescrew-threaded plug and the rod and thumb-piece for turning such plug,substantially as set forth.

3. The combination of the terminals on the outer casing the terminals onthe movable portion of the plug. and sliding electrical connectionsbetween them, substantially as set forth.

4. The combination, with a plate on the inside of the stationary casingand a band or ring on the movable plug, of a flat spring at tached tosaid plate and bearing against said band or ring, substantially as setforth.

5. The combination of the insulating parts A O and. the electricterminals carried by h them, with the plates k and c, the rod 1, andspiral spring a, substantially as set forth.

This specification signed and witnessed this 21st day of September,1882.

S 1 GM UND BERGMANN.

Witnesses RIonD. N. DYER, H. W. SEELY.

